Consolidation property of ultra soft soils before and after treatment of surface-layer improvement by vacuum preloading
LEI Hua-yang1,2,3,ZHANG Wen-zhen1,HAN Peng1,HUANG Mao-song3,WANG Xue-chao1,CHEN Li1
1. School of Civil Engineering, Tianjin University, Tianjin 300072, China; 2.Key Laboratory of Coast Civil Structure Safety of Ministry of Education Ministry,Tianjin University, Tianjin 300072, China; 3.Key Laboratory of Geotechnical and Underground Engineering (Tongji University), Ministry of Education, Shanghai 200092, China
Abstract：During the design of foundation treatment of dredger fill, it is a crucial problem to determine the consolidation properties of ultra soft soils. A series of consolidation tests with loading in increment are carried out on the ultra soft soils before and after surface-layer improvement by vacuum preloading. The consolidation characteristics and the coefficient of consolidation of ultra soft soils are investigated considering different states and directions. The test results show that the coefficient of consolidation remaines at a low level under lower stress levels. With the increasing consolidation pressure, the coefficient of consolidation has an increase, but the increment ratio decreases gradually. The ultra soft soil is different from the normal sedimentary ones, resulting in that the ratio of vertical to radial structural yield pressures of the ultra soft soils is significantly greater than that of the normally sedimentary soils. When the stress exceeds the structural yield pressure of the ultra soft soils, the radial coefficient of consolidation has no significant difference from the vertical one, and this characteristic has a large difference from that of the normally sedimentary soils.
雷华阳，张文振，韩鹏，黄茂松，王学超，陈丽. 吹填超软土浅层真空预压加固处理前后的固结特性[J]. 岩土工程学报, 2013, 35(12): 2328-2333.
LEI Hua-yang, ZHANG Wen-zhen, HAN Peng, HUANG Mao-song, WANG Xue-chao, CHEN Li. Consolidation property of ultra soft soils before and after treatment of surface-layer improvement by vacuum preloading. Chinese J. Geot. Eng., 2013, 35(12): 2328-2333.
[1] JTS 147#x02014;1#x02014;2010 港口工程地基规范[S]. 2010. (JTS 147#x02014;1#x02014;2010 Code for soil foundations of port engineering[S]. 2010. (in Chinese)) [2] 曹永华, 李 卫, 刘天韵. 浅层超软土地基真空预压加固技术[J]. 岩土工程学报, 2011, 33(增刊1): 234-238. (CAO Yong-hua, LI Wei, LIUTian-yun. Surface-layer improvement technology for ultra soft soil by vacuum preloading[J]. Chinese Journal of Geotechnical Engineering, 2011, 33(S1): 234-238. (in Chinese)) [3] 董志良, 张功新, 郑新亮, 等. 一种超软弱土浅表层快速加固系统:中国, 200720050339.8[P]. 2006.09.27. (DONG Zhi-liang, ZHENG Xin-liang, QI Guo-qing. The draindge consolidation method of soft ground without sand-cushion: China, 200610033937.4[P]. 2006.09.27. (in Chinese)) [4] 董志良, 张功新, 莫海鸿, 等. 超软弱土浅表层快速加固方法及成套技术:中国,200810026168.4[P]. 2008.07.23. (DONG Zhi-liang,ZHANG Gong-xin,MO Hai-hong,et al. The improvement method and technology of ultral-soft soil：China 200810026168.4[P]. 2008. 07.23. (in Chinese)) [5] 董志良, 张功新, 周 琦, 等. 天津滨海新区吹填造陆浅层超软土加固技术研发及应用[J]. 岩石力学与工程学报, 2001(5): 1073-1080. (DONG Zhi-liang, ZHANG Gong-xin, ZHOU Qi, et al. Research and application of improvement technology of shallow ultra-soft soil formed by hydraulic reclamation in Tianjin binhai new area[J]. Chinese Journal of Rock Mechanics and Engineering, 2001(5): 1073-1080. (in Chinese)) [6] WEBER W G. Performance of embankments constructed over peat[J]. J Soil Mech Found Div ASCE, 1969, 95(SM 1): 53-76. [7] DUNCAN J M. Limitation of convention analysis of consolidation settlement[J]. Journal of Geotechnical Engineering Division,1993,119(9)：1 333#x02014;1 359. [8] MIKASA M. The consolidation of soft clay[J]. Civil Engineering in Japan, JSCE, 1965: 21-26. [9] GIBSON R E, ENGLAND G L,HUSSEY M J L. The theory of one-dimensional consolidation of saturated clays I. Finite nonlinear consolidation of thin homogeneous layers[J]. G#x000e9;otechnique, 1967,17 (2): 261-273. [10] BO M W, CHOA Victor, WONG K S, et al. Laboratory validation of ultra-soft soil deformation model[J]. Geotechnical and Geological Engineering, 2011, 29(1): 65-74. [11] 朱耀庭, 郑爱荣, 李 卫. 吹填超软土固结特性的试验研究[J]. 湖南大学学报, 2008, 35(11): 120-123. (ZHU Yao-ting, ZHENG Ai-rong, LI Wei. Laboratory tests for the consolidation property of dredger fill in the Shenzhen area[J]. Journal of Hunan University, 2008, 35(11): 120-123. (in Chinese) ) [12] 文海家, 张永兴. 超软土的排水固结机理分析[J]. 重庆大学学报, 2002, 25(9): 82-85. (WEN Hai-jia, ZHANG Yong-xing. Analysis of mechanism of drain and consolidation of super soft soil[J]. Journal of Chongqing University, 2002, 25(9): 82-85. (in Chinese)) [13] 张 明, 赵有明, 龚 镭, 等. 深圳湾新吹填超软土固结系数的试验研究[J]. 岩石力学与工程学报, 2010, 29(增刊1): 3157-3161. (ZHANG Ming, ZHAO You-ming, GONG Lei, et al. Test study of coefficient of consolidation of fresh hydraulic fill ultra-soft in Shenzhen bay[J]. Chinese Journal of Rock Mechanics and Engineering, 2010, 29(S1): 3157-3161. (in Chinese)) [14] BUTTERFIELD R. A natural compression law for soils (an advance on e-lgp')[J]. G#x000e9;otechnique, 1979, 29(4): 469-480. [15] 李广信. 高等土力学[M]. 北京: 清华大学出版社, 2004. (LI Guang-xin. Advanced soil mechanics[M]. Beijing: Tsinghua University Press, 2004. (in Chinese)) [16] 张明鸣, 李荣玉, 张 剑, 等. 淤泥土细观渗透固结实验研究[J]. 水利工程, 2011(4): 140-144. (ZHANG Ming-ming, LI Rong-yu, ZHANG Jian, et al. Test study on microscopic permeation and consolidation of mud soil[J]. Port Waterway Engineering, 2011(4): 140-144. (in Chinese)) [17] 沈珠江. 软土工程特性和软土地基设计[J]. 岩土工程学报, 1998, 20(1): 100-111. (SHEN Zhu-jiang. Engineering properties of soft soils and design of soft ground[J]. Chinese Journal of Geotechnical Engineering, 1998, 20(1): 100-111. (in Chinese)) [18] 张诚厚. 两种结构性土的土工特性[J]. 水利水运科学研究, 1983(4): 65-71. (ZHANG Cheng-hou. Engineering quality of two kinds of structured clay[J]. Journal of Nanjing Hydraulic Research Institute, 1983(4): 65-71. (in Chinese))
